Hammer rock drills



Sept. 30,1958 whp. FISH HAMMER ROCK DRILLS Filed Jan. 25, 1955 FIG.- I.

iNvENToR: WALTER o. FISH ATTORNEY United States Patent 2,853,973 HAMMER ROCK DRILLS Application January 25, 1955, Serial No. 483,911 9 Claims. (Cl. 121-10) This invention relates to hammer rock drills and more particularly to cleansing fluid supply means for a hammer rock drill. i

In hammer rock drills of the pneumatic type, cleansing fluid is usually supplied to the bottom of the dirll hole to clear away the cuttings through a cleansing tube which extends axially through the hammer motor and communicates with a passage in the drill steel. Such a cleansing tube extends axially through an axial bore in the reciprocatory hammer piston of the drilling motor and into an axial bore of the striking block or tappet and the impact blows of the piston are transmitted through this block or tappet to the drill steel, or directly into a bore in the shank of the drill steel, and when clearances between the cleansing tube and the tappet or drill steel have been reduced sufficiently to minimize fluid leakage, it has been found that the tube frequently becomes unduly worn or broken due to the jarring action of the striking block or tappet on the steel shank. The present invention contemplates improvements over known types of cleansing tube arrangements by not only minimizing fluid leakage past the tube but also, to a substantial extert, reducing undue wear and breakage of the cleansing tu e.

An object of the present invention is to provide an improved cleansing fluid supply means for a hammer rock drill. Another object is to provide an improved cleansing fluid supply tube construction having improved sealing means at its forward portion whereby leakage of fluid past the exterior of the tube is minimized. Yet another object is to provide an improved cleansing fluid supply tube arrangement having improved sealing means at the front end of the tube whereby not only is undesired fluid leakage prevented but also undue wear and tube breakage are reduced to a minimum. These and other objects and advantages of the invention will, however, hereinafter more fully appear in the course of the ensuing description.

In the accompanying drawing there is shown for purposes of illustration one form which the invention may assume in practice.

In this drawing:

Fig. 1 is a central longitudinal section through the forward portion of a hammer rock drill in which an illustrative form of the invention is incorporated.

Figs. 2 and 3 are cross sections taken respectively on lines 2-2 and 33 of Fig. 1.

Fig. 4 is an enlarged fragmentary section taken in the plane of Fig. 1, showing details of the tube seal.

Fig. 5 is a perspective view of the sealing bushing with the latter in sealing contact with the forward end of the associated cleansing tube.

In this illustrative construction, as shown in the drawings, the invention is shown embodied in a conventional hammer rock drill of the pneumatic type comprising a cylinder or housing 1 having a rotatable front sleeve 2 and reciprocable in the cylinder is an impact element in the form of a hammer piston 3 having its forward striking portion guided within an axial bore 4' in the rotatable sleeve 2. The hammer piston of the hammer motor is actuated by pressure fluid and as it reciprocates delivers its impact blows to a rearward shank portion 5 of a striking block or tappet 6. The tappet is herein. desirably formed integral with a driver 7 to which is threadedly connected, at 8, a working implement herein desirably a drill steel 9 which carries a usual drill bit. Secured within an enlarged bore 10 in the rotatable sleeve 2 is a bushing 11 in which the shank portion 5 is supported and reciprocably guided.

Connected to the forward portion of the rotatable sleeve 2 is a rotatable driver sleeve 12 rotatably mounted in a bearing sleeve 13 fitted within a bore 14 of the front housing portion 15 of the motor cylinder. The unitary tappet and driver combination has lateral lugs 16 engaged by driver lugs 17 on the rotatable driver sleeve 12 so that as the sleeve 12 is rotated by the sleeve 2, rotation is transmitted through the lugs 16 and driver 7 to the drill steel. The forward portion of the driver sleeve 12 is formed with keyhole slots 18 whereby the lugs 16 on the tappet and driver combination may be inserted within a chamber 19 in the. driver sleeve and then turned to bring the driver lugs 16 out of registry with the key-hole slots 18 to prevent ejection of the tappet and driver combination from the driver sleeve during the drilling operation. Thus, as the drill steel 9 is percussively actuated by the hammer piston through the striking block or tappet and reciprocably driven, it is simultaneously intermittently rotated by the rotatable sleeve 2 and driver sleeve 12.

Now referring to the improved cleansing fluid supply means, it will be noted that a cleansing tube 21 extends centrally through the hammer motorwithin an axial bore 22 in the hammer piston and terminates at its forward portion within an axial bore 23 within the shank portion of the striking block or tappet 6. In order to prevent undue wear and frequent breakage of the forward portion of the cleansing tube, there is provided slight clearance between the tube exterior and the walls of the bore 23 in the tappet thereby to reduce the transmission of jars from the tappet to the tube. To reduce leakage of pressure fluid past the exterior of the cleansing tube through the bore 23 of the tappet, there is provided a reciprocable bushing 24 tightly fitting and reciprocably guided in the tappet bore 23. Arranged within the tappet bore between a shoulder 25 within the tappet and a shoulder 26 provided by a reduced forward portion 27 of the bushing is a coil spring 28 for yieldingly urging the bushing 24 into sealing contact, at 29, with the annular front end surface of the cleansing tube. Since the bushing has tight sealing contact with the walls of the bore 23 and with the front end surface of the cleansing tube, leakage past the exterior of the tube to an axial passage 30 in the driver 7 is prevented. The bushing 24 has an axial bore 31 which conducts cleansing fluid from the interior of the cleansing tube to the bore 30 and cleansing fluid may flow from the latter bore through an axial bore 32 of the drill steel to clear away the cuttings from the bottom of the drill hole.

As a result of this invention, an improved cleansing fluid supply means is provided for a hammer rock drill of the pneumatic type for minimizing leakage of pressure fluid past the exterior of the cleansing tube while at the same time preventing undue wear and breakage of the forward portion of the cleansing tube. By the provision of the clearance between the tappet bore and the exterior of the cleansing tube and the spring-urged bushing tightly fitting the tappet bore and sealingly engaging the front end surface of the cleansing tube, not only are undue wear and breakage substantially eliminated but also leakage of pressure fluid past the exterior of the cleansing tube is minimized. Other advantages of the invention will be clearly apparent to those skilled in the art.

While there is in this application specifically described one form which the invention may assume in practice, it will be understood that this form of the same is shown for purposes of illustration and that the invention may be modified in various other forms without departing from its spirit or the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is:

1. In a hammer rock drill of the pneumatic type having a percussively actuated drill steel, a hammer motor having a reciprocable piston actuated by pressure fluid and having a forward striking portion provided with an axial bore, a reciprocable member which receives the impact blows of said striking portion of the piston and having an axial bore, a cleansing tube for conducting cleansing fluid to the hole being drilled and having an annular front end surface, said tube extending axially through the hammer motor through the'bore of said striking portion and into the bore of said reciprocable member, said reciprocable member being reciprocable relative to said tube during operation of the rock drill, there being a slight clearance between the exterior surface of the forward portion of said tube and the walls of the bore in said reciprocable member, a hollow cylindrical sealing bushing tightly fitting and slidable in the bore of said reciprocable member and moving rearwardly relative to said tube sealingly to engage the annular front end surface of said tube, and means for yieldingly urging said bushing rearwardly into sealing contact with said tube to maintain a seal with the latter in all positions of said reciprocable member relative to said tube.

2. A hammer rock drill as set forth in claim 1 wherein said reciprocable member comprises a tappet engageable with the rear end of the drill steel and through which the piston blows are transmitted to the drill steel.

3. A hammer rock drill as set forth in claim 1 wherein said yieldingly urging means for said sealing bushing comprises a coil springarranged in the bore of said reciprocable member forwardly of said cleansing tube for urging said bushing rearwardly in said last mentioned bore.

4. In a hammer rock drill of the pneumatic type for percussively actuating a drill steel, a hammer motor having a reciprocable piston actuated by pressure fluid and provided with a forward striking portion having an axial bore, a reciprocable member which receives the impact blows of the piston striking portion and for transmitting such blows to the drill steel, said reciprocable member having an axial bore, a cleansing tube extending axially within the hammer motor through said bore in said striking portion into the bore of said reciprocable member and having a front end surface, said reciprocable member being reciprocable relative to said tube during operation of the rock drill, and sealing means slidingly mounted in the bore of said reciprocable member in sealing contact with the bore walls and yieldingly urged rearwardly in said last mentioned bore relative to said tube, said sealing means sealingly contacting the front end surface of said cleansing tube to maintain a seal in all positions of said reciprocable member relative to said tube.

5. A hammer rock drill as set forth in claim 4 wherein said sealing means comprises a cylindrical bushing slidingly mounted in said bore of said reciprocable member with its exterior periphery in tight sealing contact with the walls of the bore and having a rearwardly facing sealing surface.

6. A hammer rock drill as set forth in claim 5 wherein resilient means is arranged within the bore of said reciprocable member for yieldingly urging said bushing rearwardly into sealing contact with the front end surface of said tube.

7. A hammer rock drill asset forth in claim 4 wherein a slight clearance is provided between the forward portion of said cleansing tube and the walls of the bore of said reciprocable member for reducing the transmission of jars from the latter to said tube.

8. In a percussive tool for actuating a working implement, a hammer motor having a reciprocable impact element provided with an axial bore, a reciprocable member for receiving the impact blows of said impact element and having an axial bore substantially aligned with said first mentioned bore, a fluid conducting tube extending axially through said bore of said impact element into said bore in said reciprocable member and relative to which the latter reciprocates during operation of the tool, said tube having a forward end portion terminating within said last mentioned bore, a sealing bushing slid ingly received in said bore in said reciprocable member and having a rearwardly facing sealing surface, and means for yieldingly urging said bushing rearwardly in said bore in said reciprocable member relative to said tube into sealing contact with the forward end portion of said tube to maintain a seal in all positions of said reciprocable member relative to said tube.

9. A percussive tool as set forth in claim 8 wherein clearance is provided between said tube and the walls of said bore insaid impact element and said bushing substantially fits said bore in said reciprocable member in tight sealing contact with the bore-walls.

References Cited in the file of this patent UNITED STATES PATENTS 1,009,303 Hansen Nov. 21, 1911 1,461,385 Falor July 10, 1923 1,657,317 Potter Jan. 24, 1928 2,653,041 Wilson Sept. 22, 1953 2,723,136 Deubler Nov. 8, 1955 

